13-Jun-2017

Power boost for blue lasers

Blue lasers with wavelengths of the order of 450 nanometers would be ideal for processing highly reflective metals. But previously their performance left much to be desired. That is set to change.

With USD 10 million of risk capital and two experienced founders at the top, the NUBURU 2015 startup is setting out to optimize laser beam sources for 3D printing. To be more precise: blue lasers; which are to ensure greater precision, higher speed and more flexibility in the additive processing of metals.

The team working with series founders Dr. Mark Zediker and Jean-Michel Pelaprat, who can look back on a variety of managerial positions in the laser industry, were clearly not promising too much. At the LASER World of PHOTONICS 2017 in Munich, LASER 2000 will be presenting a blue high-performance laser with 150W output power at a wavelength of 450 nanometers, which was created by the US start-up and looks set to write a new chapter in the annals of laser material processing. Core advantages of blue lasers: in this wavelength range, even highly reflective metals such as copper absorb most of the laser power and also enable the light to be focused more intensely.

Not only interesting for 3D printingAt room temperature, copper alloys and gold absorb barely one-tenth of the energy of the infrared (IR) lasers that are used in material processing. Even with green and red light, the figure is hardly more than 30 percent. By comparison, if blue lasers are used, the absorption increases to almost 70 percent. Silver, titanium and nickel also absorb blue light significantly better. According to NUBURU, this high absorption is the key to markedly faster processes in laser material processing. For example, in 3D printing up to ten times higher printing speeds are possible depending on the specific alloy being processed. The start-up also hopes to speed up welding and cutting processes with these blue high-power light sources. Because the high absorption also minimizes the tendency to metal spattering, this is expected to increase precision and process quality as well as speed. Previously, spattering was always a big problem, particularly when processing copper and copper alloys.

According to NUBURU, air-cooled blue lasers also allow spot sizes up to five times smaller than with IR lasers of comparable power. This focusability allows for higher precision and print resolution—thus producing components and surfaces that are more homogeneous. Alternatively, it is possible to increase the distance between the focusing lens and the workpiece in order to process markedly larger areas compared to IR lasers.

Wide range of applicationsThe ability to precisely cut, weld and print copper, silver and nickel is interesting for users in many industries, for example in the manufacture of lithium-ion batteries for notebooks, smartphones or electric cars. Electrode material is applied to wafer-thin copper foil, which is then cut to the dimensions of the cell. Such cutting processes cannot tolerate metal chips and spatters because they can trigger dangerous short circuits and battery fires. In addition to the future market for high-voltage batteries, blue high-power lasers have set their sights on a wide range of applications in the electronics and vehicle industry. Wherever copper and precious metals have to be processed precisely and rapidly, blue light promises advantages.

But the focus is on additive manufacturing. Whether by laser application welding, or by building-up metal parts layer by layer using the powder coating process—the high absorption of this high-power beam source promises advantages. Background: In the powder coating process, lasers fuse metal powders layer by layer to form complete components, which may exhibit extremely complex geometries including arbitrary interior cavities and channels. This process is already used in aerospace, medical engineering and mechanical engineering for the manufacture of series components. More widespread industrial use is currently hampered by low process speeds and productivity, and the limited choice of materials. In this context, the precise, fast processing of precious metals and copper alloys shows up as a remarkable advance.